THE EFFECT OF UNCONVENTIONAL SILLS TO DISSIPATE ENERGY DOWNSTREAM HYDRAULIC STRUCTURES

Abstract

Water Kinetic energy downstream the hydraulic structures must be dissipated so as to stop severe scouring downstream apron and the failure of hydraulic structures. The shut block and sills with different forms are employed to disturb water and dissipate great amount of water energy through formation of a hydraulic jump in the stilling basin. Engineers have designed and used many alternative kinds of energy dissipators in order to shield hydraulic structures against scouring. The most task of the hydraulic designers is a way to dissipate a major part of water energy behind the vertical/radial gates by using more practical tools. The aim of this study is to get a better place to put the non-traditional sills to dissipate the resulting energy behind the vertical control gates. The hydraulic installations resulting from high speeds and different flows, which result in the occurrence of scour and erosion of the waterway behind these structures. The authors install a sill in several unconventional forms and study the efficient in dissipating kinetic energy. downstream hydraulic structures by installing it on relative dimensions of the gate L b / L f . Where Lf is that the length of the floor, Lb, distance from the gate, this was achieved to see the simplest position of the sill, aiming to reach the most energy dissipation and also the minimum length for the hydraulic jump. Experimental study has been conducted in glassed wall flume with square cross section of (30 cm x 30 cm) and length of 4.00 m with transparent vertical sides, located in hydraulic lab Faculty of Engineering - Al-Azhar University in Cairo, levels and water depths are measured. As well as the levels and depths of scour within the channel sector. The effect of the sill on different positions was investigated and also the results were discussed. It was found that the best place to install the sill to dissipate the energy within the middle length of the floor and also the most effective ratio is (Lb / Lf) = 0. 50.